Solutions and Other Mixtures_ongrade-04

Iced tea is an example of a solution. Iced tea is made by placing ground up tea leaves in hot water. Small particles in the leaves are then dissolved in water. The tea solution can be placed in the refrigerator to make iced tea.

Let’s compare these two glasses of iced tea.


These two glasses of iced tea are not the same color. Why? One is more concentrated than the other. A solution is more concentrated when it has more solute particles than another solution with the same volume. The second glass of iced tea has been diluted with water to make the taste less strong. The second glass has fewer solute particles for the same volume because more water was added. Both glasses are still a solution of tea particles dissolved in water. To make a solution more concentrated, you can let some of the water evaporate. The solute particles (tea particles) do not evaporate with the water, so the solution becomes more concentrated.  

We often think of solutions as liquid. However, solutions can be made with substances of any physical state of matter.

Examples of heterogeneous mixtures include:

  • sand and water
  • a salad with lettuce, tomatoes, and croutons
  • salt and pepper
  • chocolate chip cookies
  • soil (made of particles of sand, silt, clay, and humus)
Examples of homogeneous mixtures include:

  • A gas dissolved in a liquid: Carbonated beverages have carbon dioxide gas dissolved in water to provide the fizz. The carbon dioxide only stays in solution while the can is sealed.
  • A gas dissolved in a solid: Marshmallows have air whipped into a combination of hot sugar syrup and hot gelatin
 

  • A gas dissolved in a gas: The air we breathe is mainly oxygen dissolved in nitrogen.
  • A solid dissolved in liquid: Tea is made from ground particles of tea leaves that are dissolved in water.
  • A liquid dissolved in a liquid: When chocolate syrup is added to milk, you can make chocolate milk.
  • A solid dissolved in a solid: Sterling silver is made of copper and silver. Both solids are melted, and the copper dissolves in the silver.

Today you learned about different type of mixtures. Mixtures can be heterogenous or homogeneous. A solution can be made when any type of matter is uniformly distributed (dissolved) in another. There are thousands of mixtures in your everyday life. Scientists and engineers use information about mixtures to do things, like clean wastewater, make new food products, and create new medicine to help treat illnesses.